What’s in your Philly drinking water? Maybe not as much as you fear.

Philadelphia’s river water was once so foul, a doctor in 1883 offered $50 to anyone who would drink a quart of it each day for 10 days. One condition: Anyone accepting the wager could not vomit, or the bet was off.

One man tried, according to an account published in the Boston Medical Journal. But, in true Philly fashion, he added alcohol, presumably to make it go down easier.

The Delaware and Schuylkill rivers, where the city gets its water, are much cleaner than they were before the Clean Water Act of 1972. But city officials keep a constant eye on a long list of potential contaminants that are regulated — and now, some that are not.

The makeup of the water — it’s chemistry — comprises a complex range of minerals, metals, bacteria, naturally occurring compounds, as well as a range of chemicals produced for industry, farming, and even suburban lawn care. Lead and PCBs have both long been a concern, though not as much as in decades past.

But federal environmental authorities have set no firm standards for a host of chemical compounds known as “contaminants of emerging concern," though there are often guidelines. The one making the most news is per- and polyfluoroalkyl, substances known generally as PFAS. It’s the Philadelphia Water Department’s job to test for nearly 100 compounds each day. The Delaware River Basin Commission (DRBC), a federal-interstate agency with regulatory powers based just outside of Trenton, also has adopted water-quality standards and monitors what’s in the river.

This year, the Philadelphia Water Department launched a voluntary sampling program for PFAS. Chemical compounds within the PFAS family have been used in firefighting foam, and the making of stain-resistant materials and nonstick cookware. The compounds are associated with cancers, thyroid disease, immune-system problems, decreased fertility, and lower birth weight and are now being detected in food.

The Trump administration’s Environmental Protection Agency currently has an “action plan” for PFAS, but firm rules will take years, a fact that has environmental and health groups deeply concerned.

PFAS emerged as a big issue locally a few years ago when two former bases just north of Philadelphia became the first Navy sites linked to drinking water tainted by the chemicals. Public and private wells were closed in Horsham, Warminster, and Warrington because of contamination; some residents still cannot drink water from their taps, The Inquirer reported in June.

The Pennsylvania Department of Environmental Protection has begun the process of setting PFAS standards rather than wait for the EPA; New Jersey’s DEP has proposed maximum contaminant levels.

Kelly Anderson, a Philadelphia Water Department manager, said that rather than waiting for government action, her agency has started taking test samples at locations around the Delaware River watershed that are downstream from the Navy sites, and at the intakes of the three water treatment plants.

Some compounds within the PFAS family have been detected in early sampling, but at totals “all well below 70 parts per trillion," a threshold suggested in a 2016 health advisory from the EPA, Anderson said.

Is that definitely a safe level? “We’ve been following this issue for almost six years now,” Anderson said. “Our ability to detect the presence of these substances is far more advanced than our understanding of the public health implications for these substances."

»PERCEPTION: How do Philadelphians feel about their water? Everything from ‘nasty’ to not bad.

What happens if high levels of PFAS are found? Most water treatment plants — including Philadelphia’s — don’t have the technology to remove the highly soluble chemicals. Research into a cost-effective process — potentially activated carbon treatment — is underway.

The DRBC is also devoting significant time to studying PFAS.

Though lead is not a contaminant of emerging concern, it has long been a concern for city residents. Philadelphia has used wood, clay, and iron in its water mains, but it never has used lead, or even lead solder. But that’s not the case for pipes inside some older residential, municipal, and commercial properties — though no one knows how many are affected. Lead soldering has been banned since a 1986 amendment to the Safe Drinking Water Act.

Philadelphia has to run a sample test of homes known to have lead lines every three years. The last test in 2017 showed levels well below 15 parts per billion, a level set by federal rule, in 89 homes tested, according to Water Department documents.

The department adds zinc orthophosphate to water, which helps stop lead from leaching out of pipes. And, it keeps the water’s pH level neutral, as acidity in water can corrode materials that contain lead.

Ultimately, though, it’s up to a property owner to test for lead — and that can leave renters without recourse.

Stephanie Wein of the nonprofit PennEnvironment suggests residents concerned about lead buy a certified filter designed to remove it.

Opting for bottled water, Wein says, might not help. “Often, bottled water is just tap water someone is selling to them at a higher price,” she said.

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Bottled water is regulated as a food under U.S. Food and Drug Administration regulations, rather than the EPA’s National Primary Drinking Water Regulations — rules some critics say differ significantly.

Is bottled better? Not always — and it’s not even clear how often.

One “spring water” purveyor recently was revealed to be bottling municipal tap water. In June, the Center for Environmental Health said it tested bottled water and found high levels of the toxic metal arsenic in Starkey Water, owned by Whole Foods, and Penafiel, owned by Keurig Dr Pepper. Both were bottled in Mexico and sold at Target.

While some bottled-water companies use activated carbon or reverse osmosis to address PFAS, others do not. There is no comprehensive list, so bottled-water users should go to the companies’ individual websites to check.

Chemicals from pharmaceuticals and personal care products are increasingly being found at low levels in drinking water, and there’s concern they may have an impact on aquatic, and possibly, human life, according to the EPA. The chemicals act as endocrine disruptors, which means they alter normal hormonal functions, leading to reproductive effects such as small mouth bass that have characteristics of both genders.

Pharmaceuticals get into drinking water when people excrete them or dispose of them improperly, such as by flushing them down toilets. Wastewater treatment plants don’t remove them, and so they find their way into the rivers — and then drinking water. About six million people live in the Delaware River Watershed, and, with the increased use of pharmaceuticals, that’s a lot of potential contributors of over-the-counter painkillers such as acetaminophen, codeine, ibuprofen, or potent antibiotics such as lincomycin and scores of other medicines into the rivers. Hospitals and medical facilities are another source.

»THE REPUTATION: Philly’s water-treatment plants are scientific marvels. So why can’t our drinking water get any respect?

Ron MacGillivray, a senior toxicologist with the DRBC, who has given presentations on contaminants of emerging concern, said the pharmaceuticals are so diluted, they don’t threaten humans drinking the water, and are not at levels that affect most aquatic life. MacGillivray has worked with Temple University’s Water and Environmental Technology Center on the issue.

“What we’re basically seeing are similar types of compounds in urban areas,” MacGillivray said. “So the most popular medications are showing up, but ... based on the levels we have right now there are no major concerns they are causing human harm.”

Editor’s Note: “From the Source: Stories of the Delaware River” is produced with support from the National Geographic Society, the Lenfest Institute for Journalism, and the William Penn Foundation. Editorial content is created independently of the project’s donors.

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